Processes so far known for producing saccharides of definite chain length each in an isolated and highly pure form comprise hydrolyzing a glucan, such as starch, with one or more appropriate amylases and separating the desired saccharide from other unwanted oligosaccharides and/or monosaccharides by some or other known column chromatographic technique or the like [e.g. Denpun Kagaku Handbook (Starch Science Handbook), p. 452, 1987; Japanese Kokai Tokkyo Koho JP 57-209000; Japanese Kokai Tokkyo Koho JP 62-19210; Japanese Patent Publication No. 02-17158], and/or crystallizing the desired saccharide to thereby separate the same from other unwanted oligosaccharides and/or monosaccharides occurring in trace quantities (e.g. Denpun Kagaku Handbook, p. 456, 1987).
However, all the processes mentioned above intrinsically entail formation of such byproducts as glucose, uncleaved dextrin and other contaminant oligosaccharides and substantially fail to remove these unwanted saccharides from the reaction mixture.
It is known that the coexistence of an unwanted saccharide or saccharides in trace amounts markedly interfere with crystallization of the desired carbohydrate of definite chain length.
Furthermore, when the known processes mentioned above is employed for producing an oligosaccharide in a purity as high as possible, the production procedure becomes complicated, presenting problems from the yield and cost points of view.